Q.1 What does OLAP stand for in Data Warehousing?
Online Analytical Processing
Offline Analytical Processing
Online Application Processing
Object Level Analytical Processing
Explanation - OLAP stands for Online Analytical Processing, which is used for complex queries and analysis on data warehouses.
Correct answer is: Online Analytical Processing
Q.2 Which of the following best describes a data cube?
A 3D spreadsheet of data
A flat table of records
A storage unit in a warehouse
A database schema
Explanation - A data cube is a multidimensional representation of data, often visualized as a 3D spreadsheet.
Correct answer is: A 3D spreadsheet of data
Q.3 In OLAP, 'roll-up' operation refers to:
Aggregating data
Drilling down into details
Selecting a subset of data
Rearranging dimensions
Explanation - Roll-up operation summarizes or aggregates data by climbing up the concept hierarchy.
Correct answer is: Aggregating data
Q.4 Which OLAP operation provides detailed data by moving from higher-level summary to lower-level details?
Roll-up
Drill-down
Slice
Pivot
Explanation - Drill-down is the opposite of roll-up and provides more detailed views of the data.
Correct answer is: Drill-down
Q.5 What does the 'slice' operation in OLAP do?
Selects a single dimension value
Rotates the cube
Aggregates data
Provides detailed data
Explanation - Slice operation selects a single dimension of the cube, reducing it to a sub-cube.
Correct answer is: Selects a single dimension value
Q.6 The 'dice' operation in OLAP involves:
Selecting a subset of dimensions and values
Summarizing data
Rotating cube dimensions
Filtering only one record
Explanation - Dice operation selects data based on multiple dimensions, forming a smaller cube.
Correct answer is: Selecting a subset of dimensions and values
Q.7 Pivot operation in OLAP is used to:
Rotate the data cube axes
Aggregate data
Slice a cube
Drill down details
Explanation - Pivot allows reorientation of the cube for different perspectives of data analysis.
Correct answer is: Rotate the data cube axes
Q.8 Which of these is NOT a typical OLAP operation?
Roll-up
Drill-down
Cluster
Slice
Explanation - Clustering is a data mining task, not an OLAP operation.
Correct answer is: Cluster
Q.9 OLAP tools are mainly used for:
Transactional processing
Data analysis
Data entry
Networking
Explanation - OLAP is primarily used for analytical processing of large volumes of data.
Correct answer is: Data analysis
Q.10 Which type of OLAP system stores data in relational databases?
MOLAP
ROLAP
HOLAP
SOLAP
Explanation - ROLAP (Relational OLAP) stores data in relational databases.
Correct answer is: ROLAP
Q.11 MOLAP stores data in:
Relational tables
Multidimensional cubes
Flat files
Key-value stores
Explanation - MOLAP (Multidimensional OLAP) stores data in precomputed multidimensional cubes.
Correct answer is: Multidimensional cubes
Q.12 Which OLAP approach combines ROLAP and MOLAP?
SOLAP
HOLAP
DOLAP
COLAP
Explanation - HOLAP (Hybrid OLAP) uses both relational storage and multidimensional storage.
Correct answer is: HOLAP
Q.13 The star schema is commonly used in:
OLTP
OLAP
AI systems
Networking
Explanation - Star schema is a popular database schema for OLAP systems.
Correct answer is: OLAP
Q.14 Which schema has multiple fact tables?
Star schema
Snowflake schema
Fact constellation schema
Hierarchical schema
Explanation - Fact constellation schema contains multiple fact tables and is more complex than star schema.
Correct answer is: Fact constellation schema
Q.15 What is a dimension table in OLAP?
A table that stores transactional data
A table that stores descriptive attributes
A table that stores foreign keys only
A table with only one record
Explanation - Dimension tables store descriptive information used to analyze facts.
Correct answer is: A table that stores descriptive attributes
Q.16 Which schema normalizes dimension tables?
Star schema
Snowflake schema
Fact constellation schema
Mesh schema
Explanation - Snowflake schema normalizes dimension tables into multiple related tables.
Correct answer is: Snowflake schema
Q.17 OLAP queries are typically:
Read-intensive
Write-intensive
Both read and write equally
Transaction-focused
Explanation - OLAP queries mainly involve reading and aggregating data rather than writing.
Correct answer is: Read-intensive
Q.18 Which OLAP category is most scalable with large datasets?
MOLAP
ROLAP
HOLAP
DOLAP
Explanation - ROLAP is more scalable because it uses relational databases that handle large datasets efficiently.
Correct answer is: ROLAP
Q.19 In OLAP, fact tables usually contain:
Only descriptive attributes
Only dimension keys and measures
Only one measure
Only textual data
Explanation - Fact tables store quantitative measures along with foreign keys to dimension tables.
Correct answer is: Only dimension keys and measures
Q.20 Which OLAP model precomputes aggregations for fast query response?
ROLAP
MOLAP
HOLAP
SOLAP
Explanation - MOLAP precomputes and stores aggregations in multidimensional cubes, making queries faster.
Correct answer is: MOLAP
Q.21 What is the main disadvantage of MOLAP?
Slow queries
Storage overhead due to precomputed cubes
Lack of aggregation
Low accuracy
Explanation - MOLAP requires significant storage due to precomputing and storing multidimensional data cubes.
Correct answer is: Storage overhead due to precomputed cubes
Q.22 In OLAP terminology, measures are:
Quantitative data
Qualitative data
Dimension keys
Metadata
Explanation - Measures are numerical values like sales, revenue, or profit that are analyzed in OLAP.
Correct answer is: Quantitative data
Q.23 Which of these is an example of a dimension in OLAP?
Revenue
Profit
Time
Sales amount
Explanation - Dimensions are descriptive attributes such as time, location, or product.
Correct answer is: Time
Q.24 Which OLAP system is most suitable for small datasets with fast response time?
ROLAP
MOLAP
HOLAP
SOLAP
Explanation - MOLAP is best for smaller datasets due to its fast response using precomputed cubes.
Correct answer is: MOLAP
Q.25 Which schema is easiest to understand and widely used for OLAP?
Star schema
Snowflake schema
Fact constellation schema
Hybrid schema
Explanation - Star schema is simple and intuitive, making it the most commonly used in OLAP.
Correct answer is: Star schema